Preview at WWDC likely in June, followed by September launch.
France Telecom CEO Suggests October 15th Launch Date for iPhone 5
If I believe what we heard, the iPhone 5 will be released on October 15.Richard has a history of speaking rather openly about issues related to the carrier's business, including discussing Apple's desire to reduce the size of or eliminate SIM cards in its GSM-compatible devices, moving to a built-in "e-SIM". That idea has been opposed by carriers, and Apple has reportedly backed away from its e-SIM plans for at least the time being.
October 15th falls on a Saturday, which would be an unusual launch date for Apple, which prefers to launch its new iPhone models on Thursdays or Fridays. Consequently, some have suggested Friday, October 14th as the most likely date for a debut, although others have claimed that Apple could roll out the new hardware a week earlier on the 7th.